Sex reassignment may refer to:

• Sex reassignment, changing the sex assignment of an infant or child by parents and doctors, usually because of fuller understanding of an intersex condition.
• Sex reassignment, changing the social sex of an older child or adult who asserts a gender identity opposite to his/her biological and originally assigned sex.
• Sex reassignment therapy, an umbrella term used to describe all medical procedures regarding gender reassignment of both transgender and intersexual people
• Sex reassignment surgery, a term for the surgical procedures by which a person's physical appearance and function of their existing sexual characteristics are changed to that of the other sex